Sources of variation and Natural Selection

What is natural selection?

A process that drives evolutionary change by favouring individuals with advantageous characteristics.

What theory explains evolution by natural selection?

Charles Darwin’s theory of evolution.

Why is variation essential for natural selection?

Without variation, no individuals would be favoured over others.

What did Darwin observe about populations?

That individuals vary in many characteristics.

What would happen if all individuals were identical?

Natural selection could not occur.

What generates variation within a species?

Mutation and sexual reproduction.

What role does mutation play in variation?

It creates new alleles by changing DNA sequences.

Do all mutations affect phenotype?

No, many have no effect, but some can be harmful or beneficial.

What role does sexual reproduction play in variation?

It produces new combinations of alleles.

What is crossing over?

Exchange of DNA between homologous chromosomes in prophase I of meiosis.

What is independent assortment?

Random arrangement of maternal and paternal chromosomes during metaphase I.

How does random fertilisation increase variation?

Any gamete can fuse with any other gamete.